Fluid fuel burner control



.'May 31, 1938. r J. P. KRIECHBAUM 03 FLUID FUEL BURNER CONTROL Filed, Jan. 23, i936 50 action of the other valve.

Patented May 31, 1938 UNITED s'rATss PATENT mm mf$hfi;m$

or to MinneapolivHoneyweli Regulator Company, Minneapolis, Minn a corporation of Delaware Application January 23, .1938, Serial No. 60,481

8 Claims. (01. iss-zs) My invention relates to a fluid fuel burner control and more particularly to a control for a gas burner employing the pilot burner to ignite the same, which pilot burner is lighted only when the burner is to be put into operation and during such operation.

In certain types of gas burner control systems it is the practice to provide means for igniting the pilot burner each time that it is desired to 10 place the main burner into operation. In such systems, a valve is usually provided for con"- trolling the supply of gas to the pilotburner and some means is providedfor igniting the gas supply to the pilot burner. In addition, it is customary as a safety measure to provide. a thermostatic device responsive to the presence of aflame at the pilot burner, commonly known as a "safety pilot thermostat". This device is employed to prevent the main gas valve being opened until thepilot burner has been lighted.

Arrangements, have also been provided, which utilize the safety pilot thermostat to place the ignition means out of operation after the pilot has been lighted.

,The prior systems of this type have all had certain definite disadvantages. In one such system the main valve is controlled only by the safety pilot thermostat'and is not under the control of the room thermostat.- If for any reason, the pilot valve is stuck in an open position, there is a possibility in this system of a dangerous condition being created by reason-of the con tinued operation of the main-burner after the thermostat ceasesto call for heat. Another type of system overcomes the disadvantage just mentioned by employing a relay which adds to the expense and complication of the system.

An object of the'present invention is to provide a system of a similar type just, discussed 40 wherein the main valve is under control or both the thermostat and the safety pilot and wherein the use of a relay is eliminated by the utilization of a switch operated by the operating means for the pilot valve.

215 Afurth'erobject of this invention is to provide a control system employing .a plurality of valves in which a switchactuated in connection with the op'eningof one of the valves controls;

.in conjunction with a thermostatic switch, the

A further object or the present invention is to provide a burner control system in which the circuit to the ignition means'for the burner is controlled by a switch which'is closed upon open- .66 movement of the burner valve. Y Y I i Otherobjects of the invention will be apparent upon a consideration of the accompanying specification, claims, and drawing.

In the single figure of the drawing, I have shown a preferred form of my invention in a more or less schematic manner. Referring. to said figure, a; main gas burner is designated by the numeral I0 and a pilot burner by the numeral i I. The main burner is connected through a. pipe l2 and a main valve It with a gas supply pipe ll. Connected to the gas supply pipe on the inlet side of valve i3 is a pipe l5 which supplies fuel to the pilot burner ll under control of a pilot valve ll.

Located in proximity to the pilot burner ll is a safety pilot thermostat "II. This safety pilot thermostat may be of any conventional form wherein switch means are provided so that when the pilot is cold one set of contacts are in en-' gagement and when the pilot is hot another set is engaged. In the schematic showing of the safety pilot. thermostat in thedrawin'g, the temperature sensitive element which is shownas a bimetallic element is indicated by referencenumber ID. This bimetallic element is adapted to be engaged with either of two contacts, and II. when the pilot burner is not lighted and the safety pilot thermostat is cold,- as indicated'in the drawing, the bimetallic element It is in engagement with the contactv 20, which contactmaybe referred to as the "cold contact.- When the pilot burner is lighted, "thebimetallic ele-' vment is deflected to the left so as ,to be in engagement with the contact 2i, which contact may be referred to as the hot contact. l

Located in proximity to the pilot burner II are two electrodes 24. which are spaced apart to provide a spark gap therebetween. These electrodes are connected to the opposite terminals of a secondary 25 of a step-up spark transformer 20. The transformer 28 has inaddition to the high -voltage mary 21. I

secondary 28, a low voltage prl- .A step-down transformer ll supplies ppwer for i the operation of my This transformer voltage secondary I I The primary 3. is connected to line wires 32 and 38.

moral ll. This-thermostat may take any conventional form and-may be responsive to any The thermostat controlling the operati v y'lystem is designated .by the'refer'ence nucontrolling'condition. In the present case, Qtlfe thermostat is intended to be a mom thermostat comprisesa line voltage primary 3! and slow is attached a contact arm 88 adapted to be moved into engagement with contacts 81 and 88. It

will be noted that the contact arm 88 is less widely spacedfrom contact 81, than from contact 38. Thus upon movement of the contact arm 88 in the direction of contacts 81 and 88-, the contact arm is first moved into engagement with bimetallic element 35 is so arranged that contact arm 88 is moved'in the direction of contacts 81 and 38 upon a decrease in'the temperature.

The main gas valve I8 may be of any type employing electrically actuated means for openin; the valve. For purposes of illustration, I have shown an actuating means f the stalled motor" type, wherein the valve is opened by a motor against the action of a spring which tends to move a valve to a closed position and which, upon deenergization of the motor. so moves the valve. The motor of this actuating means is designated by the reference numeral '48 and comprises a rotor 4i and held winding 42. The rotor 4i is connected through a suitable reduction gearing 43 with a gear 44. a pin 45, which pin is adapted to engage with the curved-portion of a hook 41. The hook 41 is pivotally connected to a lever 48, which in turn, is connected to a valve stem 48 of the valve ii. A valve stem 48 is connected to a valve disk 88 which is biased to a closed position by a spring Upon energiz ation of the motor, the gear 44 is rotated in the direction of the arrowv shown thereon causing the pin 45 to engage the hook 41 and to raise the lever 48 and accordingly the valve 58. A pin 52 is secured to any suitable support and limits the upward movement of lever 48 and consequently of the valve 88. Upon deenergization of the motor, the spring is eflective to move the valve downwardly, moving therewith the gear train 48 and the motor 48 and returning them to the position shown in the drawing.

Although the pilot valve may be in the form oi. any power actuated valve with provision for a switch actuated upon the energlzation of the valve actuating means, I have shown for purposes of illustration, a solenoid valve-having a switch which is moved to closed position upon energization of the solenoid. This valve may con-- veniently be of the form of the valve disclosed in the co-pending application of Willis H. Gille,

Serial Number 39,781, filed September 9, 1935 I have shown this valve schematically as comprising a valve body 54 on which is mounted a solenoid coil 58, with which is associated a core 58 of magnetic material. The core is attached to a valve disk 81 so that upon energization of the solenoid coil 55 with the resulting upward movement of the core 58, thevalve 'disk 51 is moved into open position. Also associated with the solenoid 88 is a switch comprising a switch blade 88 to which is secured an armature member 88. Upon energization of the solenoid, the armature member 58 and accordingly the switch blade 58 is moved downwardly, to cause engagement of the switch blade with a stationary contact 88.

The various members are shown in the drawing .in the position they assume when the temperature in the space to be heated is at or above the desired value. Upon the temperature dropping below this value, the contact arm, is moved in the direction of contacts 81 and 88. The contact arm 88 will first engage contact 81 but 1 8 en- Securedto this gear 44 is gagement will not cause the establishment of any energizing circuit. If the temperature continues to drop, however, the contact arm 88 will be moved into engagement with bothcontacts 81 and '88, causing the following energizing circuit to be established: from the right hand .terminal of secondary 8i through conductors 82 and 83, contact 88, contact arm 88, contact 81, conductor 84, solenoid winding 85 andconductors 88, 88 and 81 to the left 'hand terminal of secondary 8|. This causes the energization of solenoid winding 58 with the result that switch blade 58 is moved into engagement with contact 88 and the valve I8 is opened to admit gas to the pilot. At the same time the following circuit is established through the primary 21 of the spark transformer 28: from the right hand terminalof secondary 3i, through conductors 82 and 88, contact 88,

contact arm 88, bimetallic element 85, conductor 88,conductor 88,bimetallic element I8,contact 28, conductor 18, primary 21, and conductors 1i, 88, and 81 to the left hand terminal of secondary ii.

The moving of switch blade 88 into engagement with contact 88 as the result of energlzation of solenoid winding 58 causes the following holding circuit to be establishedto. the solenoid winding: from the right hand terminal of secondary 8| through conductors 82 and 12. contact 88, switch blade 58, conductors 18 and 88, bimetallic element 85, contact arm 88, contact 81, conductor 84, solenoid winding 58, and conductors 85, 88 and 81 to the left hand terminal of secondary 8|. At the same time, a holding circuit is established through the primary of spark transformer 21 as follows: from the right hand terminal of secondary 8|, through conductors 82 and 12, contact 88, switch blade 88, conductors 18 and 88, bimetallic element I8, contact 28, conductor 18, primary 21, and conductors 1i, 88 and 81 to the left hand terminal of secondary 8i. The result of the establishment of these two holding circuits is that the solenoid valve will remain open and the spark transformer will remain energized even though contact arm 88 should move away from contact "as might occur because of some slight vibration or very slight temperature fluctuation.

,In this manner sudden starting and stopping ofthe apparatus is avoided.

The result of the opening of the pilot valve I8 and the energization of the sparktransformer 28 is that the two conditions necessary for ignition of the pilot burner have been established. If the apparatus is functioning properly, the gas supply to the pilot burner II by reason of the valve I8 being open will be ignited by a spark appearing across the electrodes 24 by reason of the energization of the spark transformer 28. After the pilot burner is lighted, the bimetallicvelement I8 of thesafety pilot thermostat I! will soon become heated with the result that the element I8 is moved out of engagement with the cold contact 28 and into engagement withthe hot contact 21. The moving of the bimetallic eleinent I8 out of engagement with contact 28 results in the circuit through primary 21 and the ignition transformer --being broken. This causes the deener'gization of the ignition transformer, the operation of which is no longer needed by reason of the pilot burner being lighted.

The, moving bf the bimetallic element "into engagement with the hot contact 2i results in the following circuit being established through 'fleld winding 4.2 of the motor 48 which aetuates the main .gas valve:" from theright hand terminal of secondary 8i through conductors 82 and 12, contact 60', switbh blade 58, conductors l3 and 8'9, bimetallic element I 9, contact 2|, conductor 15, motor field winding 42, and conductor 61 to the left hand terminal of secondary 3|. This results in the energization of the motor 40 causing the same to rotate the gear 44 in the direction of the arrow thereon and hence causing the opening of the main gas valve l3 as previously explained. The opening of the main gas valve permits gas to flow to the main burner l0 where it is ignited by the pilot burner. The main burner will then continue in operation until the temperature in the room or in the space to be heated has risen sufilciently that contact arm 36 is separated from contact 31 causing the deenergization of the entire system 'and restoring the parts to the positions shown in the drawing.

It will be noted that the field winding 42 of the motor operating the main gas valve is-under control of both the safety pilot thermostat and the room thermostat. The control of the main gas valve motor by the thermostat is effected through switch 58 and. contact which remain closed only so long as the thermostat is calling for heat. The moment that the contact arm 36 separates from contact 31, the solenoid winding 55 is deenergized permitting separation of switch blade 58 from contact 60 thus interrupting the circuit to the field winding 32; It will further tion means and also to control the main valve motor. In this manner, I have obtained a relativelysimple and inexpensive control system in which a minimum of parts are employed but in which absolute safety in the event of any contingencies is assured.

While I have shown a specific embodiment of my invention, it is to be understood thatv this is for purposes of illustration only and that my invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a fluid fuel burner control system, a pilot burner, a main burner, a pilot burner valve, a main burner valve, an electric motor for operating each of said valves, a switch associated with the pilot valve motor, said motor being operative upon energization thereof to open said pilot valve and close said switch, a switch responsive to a- 2. In combination, a plurality of valves, an

electric motor for each of said valves, a switch associated with one of said motors, said motor being operative when energized to move itsassociated valve from a first to a second controlling position and to simultaneously close said switch, a switch responsive to a condition and having a pair of contacts which at a predetermined value of said condition are moved into unstable engagement 'with each other, a source of energy. circuit means controlled by said pair of connecting said'motor associated with said switch with said source of energy, holding circuit means for said motor independent of said pair of contacts and controlled by said first named switch, and energizing circuit means for the other of said motors including and controlled by said first named switch.

3. In combination, a plurality of valves, an electric motor for each of said valves, a switch associated with one of said motors, said motor being operative when energized to move its associated valve from a first to a second controlling position and to simultaneously close said switch, a switch responsive to a. condition and having two sequentially engageable pairs of contacts, a source of energy, circuit means controlled contacts of said condition responsive switch for by both pairs of contacts of said condition responsive switch for connecting said motor associated with said switch with said source of en'- ergy, holding circuit means for said motor independent of the last to be engaged of said pairs of contacts and controlled by said first named switch, and energizing circuit means for the other of said motors including and'controlled by said first named switch.

4. In a fluid fuel burner control system, a pilot burner, a main burner, a pilot burner valve, a main burner valve, an electric motor for operating each of said valves, a switch associated with the pilot valve motor, said motor being operative upon energization thereof to open said pilot valve and close said switch, a switch responsive to a controlling condition and comprising a pair of contacts which at a predetermined value of said condition are moved into unstable engagement with each other, a source of energy, circuit 'means controlled by said pair of contacts of said condition responsive switch for connecting said pilot valve motor with said source of energy, holding circuit means for said motor independent of said pair of contacts and controlled by said first named switch, and energizing circuit means for said main valve motor including and controlled bysaid first named switch. 7

5. In a fluid fuel burner control system, a pilot burner, a main burner, a pilot burner valve, a main burner valve, an electric motor for operating.each of said valves, a switch associated with the pilot valve moto'r, said motor being operative upon energization thereof to open said pilot valve and close said switch, a switch responsive to a controlling condition and comprising two sequentially engageable pairs of contacts, a source of energy, circuit means controlled by both pairs of contacts of said condition responsive switch for connecting said pilot valve motor with said source of energy, holding circuit means for said motor independent of the last to be engaged of said pairs of contacts and controlled by said first named switch, and energizing circuit means for said mainv valve motor including and conmined value of said condition are moved into unigniting said pilot burner, a temperature re sponsive switch adJacent to said pilot burner and moved to closed position when subjected to the heat of the pilot flame, and energizing circuit means'for said main valve motor includin and controlled by said first named switch and by saidtemperature responsive switch.

7. In a temperature control system, apparatus employing a fluid, a valve controlling the flow of 7 said fluid to said apparatus, an electrical motor for operating said valve, a switch comprising a single pair of contacts associated with said motor, said motor being operative upon energize- Jion thereof to movesaid valve from a first to a second controlling position and to simultaneously close the contacts of said switch, a-swltch responsive to the temperature of a controllingmedium and having a' pair of contacts which at a predetermined value of said condition are moved into unstable engagement with each other, a source '0! energy, circuit means controlled by said pair of contacts of said condition responsive switch for connectingsaid motor with said source of energy, holding circuit means for said motor independent of said pair of contacts of said condition responsive switch and including and controlled bysaid first named switch, turther electrically operated apparatus whose operation prior to the movement of said valve-to said second controlling position is not desirable, and

circuit means also including and controlled by said first named switch for energizing "said fur--" ther apparatus.

8. In a temperature control system, apparatus employing a fluid, a'valve controlling the flow of said fluid to said apparatus, an electrical motor for operating said valve, a switch comprising a single pair of contacts associated with said motor, said "motor being operative upon energization thereof to move said valve from afirst tora second controlling position. and to simultaneously close the contacts of said switch, a switch responsive to the temperature of a controlling medium and having a pair of contacts which at a predetermined value of said condition are moved into unstable engagement with each other, a source of energy., circuit means controlled by said-pair of contacts of said condition responsive switch for connecting said motor with said source of energy, holding circuit means for said motor independent of said pair of contacts of said condition responsive switch and controlled by said first named switch, a third switch, and means responsive to a condition normally established as a result of the movement 01 said valve to said second controlling position and operative upon the establishment of said condition to move said third switch toclosed position, further electrically operated apparatus whose operation prior to the establishment of said last named condition is not desirable, and

circuit means including and controlled by said first named switch and by said third switch for energizing said additional apparatus.

JOHN P. .KRIECHBAUM. 

